How do you know when the best time is to harvest your herbs? The truth is, to determine the best harvest time for each herb, you need some practice. With time you will get to know the plants you work with and recognize when they are at their optimum and how best to process them. The general rules listed below will also lead you in the right direction for most herbs. Expect some failures – leaves that turn brown when dried or herb bundles that go mouldy in the middle; it is part of the learning process. Don’t despair; following the guidelines below should help to minimize any harvesting problems.
Harvesting herbs is really very simple, much like harvesting food from your garden. Tools you may need are a shovel for roots, scissors or a sharp pocketknife for tough-stemmed plants, and a pruning saw to cut branches for barks. Allow yourself time after a harvesting expedition to process the herbs before they wilt or lose vitality.
Several things to consider before you start harvesting - herbs should be harvested in clean, unpolluted areas away from roadsides, sprayed farm fields, toxic dump sites or other suspect activity. Harvest in places where there is an abundance of the plant you are gathering. A general rule of thumb is to only gather 1/3 or less of the same species in any given area to ensure sustainable harvest sites.
Tips for successful harvesting include:
· Harvest the leaves when they contain the optimum amount of volatile oils. These oils give herbs their special flavour or scent and have strong medicinal actions. Ideally you should cut herbs soon after the dew has evaporated from the leaves in the morning. Harvest on a dry day that has been preceded by at least two sunny days.
· In most cases, cut stems for harvest when the flower buds are just beginning to open. Plants that are part of the Mint Family (peppermint, lemon balm, motherwort etc.), however, have the most oil in the leaves when the spikes are in full bloom.
· You can cut back a perennial herb to about half its height and can cut down an annual to a few inches. You can also remove an annual completely near the end of the season.
· When gathering a large quantity of herbs, use an open-weave basket or containers that allow good air movement. Don't stuff herbs into plastic bags, which can heat up and cause rapid deterioration of herbs.
· Make sure you wear gloves when picking herbs that can irritate the skin such as nettles, comfrey, and borage or that are phototoxic such as yarrow, rue and Queen Anne’s lace.
· Carefully harvest plants such as red clover and plantain, they bruise easily (turn brown). Don’t layer them in harvesting baskets more than three layers deep and put them in a single layer on screens to dry.
· Never harvest more than you can conveniently dry at one time and never more than you think you will need. Harvesting too much is a waste and deprives bees, butterflies and other beneficial insects of pollen and food.
· Herbs have a limited shelf life so try to harvest only what you think you will use in the suggested time frame. Leaves and flowers keep 1-2 years if cared for properly. Roots, barks, and seeds keep up to 3 years, sometimes longer.
· It is best not to wash the leaves and flowers of plants, if at all possible. If dirt is a problem try to gently brush it off. If this is not successful then wash the plants in cool water immediately after gathering and spread them on towels. Pat them gently with a towel until moisture free.
· Roots need to be washed carefully (a vegetable brush works best) and then cut into small pieces and spread on trays or screens to dry. A food processor works great to chop most roots. Some people dry their roots whole, but this can be problematic as it can be difficult to cut some herbs once they are dry and this makes them very difficult to use for teas and other formulas later.
· Drying plants outside can be sometimes challenging as temperature and humidity changes can cause your plants to turn brown or mould. It is advisable to dry your herbs indoors whenever possible.
· A dark, well-ventilated room where temperatures run between 70 – 90°F/ 20 - 30°C is an excellent room for drying. A circulating fan set on low can increase air circulation and dry plants faster. Air conditioning can be helpful because it reduces humidity in the air.
· You can use frames covered with cheesecloth or other netting, or mesh window screens for drying. Prepare the frames or screens before you cut the plants.
· For some herbs, you strip the leaves from the stems before drying. Herbs in this group include comfrey, mullein, and other larger leafed plants. Spread these leaves in single layers for quickest drying.
· Herbs with smaller leaves can be dried in bundles on the stems. These herbs include lavender, thyme, mint, rosemary, and lemon balm. Keep the bundles small so that the centre of the bundle has some air circulation as this will help prevent mould happening in the centre of the bundle. Strip the leaves after drying is complete.
· Herb leaves should dry in three to four days under proper conditions but make sure they are completely dry before putting in a jar or they could go mouldy. If the leaves crumble fairly easily then that is generally an indication that they are fully dry. In humid weather, you may need to spread the herbs on a cookie sheet and dry them in an oven at about 125°F/50°C.
· To harvest roots dig them in the late fall or early spring when the plant is dormant, and the root is most potent. Wash them thoroughly after digging. Then slice or split the large roots. Place the pieces in thin layers on screens and turn the slices several times a week. It may take roots six to eight weeks to dry completely. When dry, the root piece should snap when you bend it.
· Drying seeds and berries from plants such as fennel, anise, juniper berries, elderberries and dill can be done using a paper bag. Gather seeds once they are dry on the stem and berries preferably after the first frost. Handle carefully as the ripe seeds/berries shed easily. Cut seed heads into a paper bag and hang open bags in airy spot under roof for 2 to 3 weeks to finish drying then spread out on paper to finish drying. When dry and papery, shake seeds/berries loose and blow or sieve chaff away.
· When harvesting bark, it is best done when the sap is high in the Spring and the Fall. Peel the bark off the branches in thin strips with a very sharp knife. Then cut the strips into smaller pieces with sturdy scissors. The inner bark is what you are after, but it is okay to leave the outer bark on, too. It is best to try and take the bark off the branches rather than the trunk of the tree if possible. If you do take off the trunk, make sure you take only from one side of the tree or you will do what is known as “ringing” the tree which can kill it. To dry the bark spread it on screens.
Harvesting your own herbs and botanicals is fun and rewarding. It is a great chance to get outside and enjoy nature and, if you have children, it is a great way to introduce them to the many uses of plants. So off you go, have fun, and feel free to ask questions about gathering plants in the comments below or share with us your herbal harvesting adventures.
Oh and if you leave us a comment we will email a great chart to you that tells you the best time to harvest a wide range of plants!